Fix ART build with host gcc >=4.7

Signed-off-by: Paul Beeler <sparksco@gmail.com>
Signed-off-by: Peter Carenza <pcarenza@gmail.com>
Use HOST_CC for host

Signed-off-by: Paul Beeler <sparksco@gmail.com>
Fix NewLocalRef, NewGlobalRef to handle cleared weak globals.

We were not checking for null after decoding the reference, this
meant that we incorrectly created null weak global references instead
of returning null.

Issue: 63929
Change-Id: I9159682e6edad8f415ef8144fc13b9aedd2cceb4
art: fix boot in art mode

It's a bug in libcore

origin commit is GC triggering performance optimizations
SHA1 ID: 7646e2eb41024d152d76b269653c2321e2cfbd23

URL: https://github.com/CyanogenMod/android_libcore/commit/7646e2eb41024d152d76b269653c2321e2cfbd23

Change-Id: I5ec4ae74dc70f1859db2bae8588e697b147a2682